1. Field of the Invention
The present invention relates generally to the transmitting and receiving of a signaling message in a communication system and, in particular, to a communication system including a control unit for transmitting a signaling message at varying margin levels and a plurality of mobile radio telephones which provide a signal to alert a user thereof when a signaling message is received through a paging channel having a margin level greater than a specified margin level.
2. Description of Related Art
The present invention relates to a communication system and the manner in which a mobile radio telephone is signaled by the system that a message is pending for reception. For example, a satellite communication system will generally include a land-based control unit for formatting a signaling message and a land earth station (known as an LES) which receives the signaling message from the control unit. The LES then transmits the signaling message to a mobile satellite phone by means of a paging channel via an intermediate satellite. Under advantageous conditions, the mobile satellite phone is able to acquire synchronization to the paging channel. At other times, such as when the phone antenna is not deployed or the phone is shadowed inside a building, the mobile satellite phone is unable to acquire synchronization.
While it is possible for a paging channel to be provided which has a higher than normal margin level, this generally stems from an increase in power which consumes valuable resources of the satellite communication system. Another disadvantage of using such a high margin paging channel is that the mobile satellite phone is usually unable to reliably acknowledge any signaling message received because of insufficient link margin. This results from the limited peak transmit power of the mobile satellite phone, which is inadequate to provide the reverse-link equivalent of such a high margin paging channel.
Several techniques for addressing these problems have been disclosed in a series of patent applications by the owner of the present invention. These patent applications are entitled "High-Penetration Transmission Method For A Radiocommunication System" (Ser. No. 08/559,692), "High-Penetration Transmission Method For A Radiocommunication System" (Ser. No. 08/579,015), "High Power Short Message Service Using Dedicated Carrier Frequency" (Ser. No. 08/588,507), and "High Power Short Message Service Using TDMA Frames" (Ser. No. 08/578,945), each of which are also owned by the assignee of the present invention and hereby incorporated by reference. The prior identified patent applications are suitable for their intended purposes, but the present invention further provides an approach which involves transmission and/or receipt of the signaling message in the communication system.
In light of the foregoing, a primary objective of the present invention is to provide a mobile radio telephone which generates a signal to alert the user thereof when a message is received other than through a normal paging channel.
Another object of the present invention is to provide a mobile radio telephone which generates a variety of different signals to alert the user thereof when a signaling message is received other than through a normal paging channel.
A further object of the present invention is to provide a mobile radio telephone which permits the user thereof to select the type of alerting signal generated when a signaling message is received other than through a normal paging channel.
Yet another object of the present invention is to provide a mobile radio telephone which transmits an acknowledgment signal when it receives a signaling message through the normal paging channel.
Still another object of the present invention is to provide a mobile radio telephone which generates a signal to alert the user thereof when it receives a signaling message through a paging channel having a higher margin level than the normal paging channel.
It is another object of the present invention to provide a mobile radio telephone which is able to distinguish between a plurality of paging channels having distinct margin levels.
An object of the present invention is to provide a mobile radio telephone which generates a signal to alert a user thereof when it receives a signaling message through a paging channel having a margin level greater than a specified margin level.
Another object of the present invention is to provide a method of alerting a user of a mobile radio telephone when a signaling message is received through a paging channel other than the normal paging channel.
A further object of the present invention is to provide a method of alerting a user of a mobile radio telephone when a signaling message is received through a paging channel having a margin level greater than a specified margin level.
It is another object of the present invention to provide a control unit for a communication system which is able to transmit a signaling message at varying margin levels to a mobile radio telephone.
Another object of the present invention is to provide a control unit for a communication system which exchanges messages with a mobile radio telephone upon receipt of an acknowledgment signal from the mobile radio telephone indicating receipt of a signaling message from the control unit at a specified margin level.
Still another object of the present invention is to provide a control unit for a communication system which is able to transmit a signaling message at varying margin levels to a mobile radio telephone via a single paging channel.
Yet another object of the present invention is to provide a control unit for a communication system which is able to transmit a signaling message at varying margin levels to a mobile radio telephone via a plurality of paging channels in which each paging channel has a distinct margin level.
Another object of the present invention is to provide a method of transmitting a signaling message between a control unit of a communication system and a mobile radio telephone at increasing margin levels until the mobile radio telephone receives the signaling message.
A further object of the present invention is to provide a communication system including a control unit for transmitting a signaling message at increasing margin levels to a mobile radio telephone thereof until the mobile radio telephone receives the signaling message.
These objects and other features of the present invention will become more readily apparent upon reference to the following description when taken in conjunction with following drawing.